The present invention relates to nock assemblies for arrows. More specifically, the field of the invention is that of nock adapters for arrows.
Arrows consist of three basic varieties of shafts: aluminum, carbon, and aluminum-carbon. Each variety has a number of different sizes, all with common problems which are inherently involved in mounting nocks. Also, the cost of the arrow shaft is significantly greater than the cost of a nock, so protecting the shaft has considerable importance in the archery art.
About 50 different sizes of aluminum arrows are commonly used. Typically, the shaft of an aluminum arrow is a cylindrical tube with an inner bore and a relatively thin rigid outer wall. On prior art aluminum arrows, an end portion of the arrow is tapered by swedging to produce a 111/2.degree. tapered nock mounting surface for supporting nock attached thereto by adhesive. However, swedging produces a tapered surface which is often off-center or split and thus causes problems in the performance of the arrow such as erratic flight paths. Also, swedging is a relatively expensive operation which creates a significant amount of scrap.
To avoid swedging, prior art nock adapters are provided for are insertion into a hollow end of an arrow to provide a nock mounting surface. One such nock adapter is described in co-pending application "Nock Insert For An Arrow", Ser. No. 463,894, the disclosure of which is expressly incorporated by reference herein. These prior art adapters are well suited for mounting standard nocks on aluminum arrows, but are not suited for some other arrow types such as carbon or aluminum carbon arrows.
About 12 to 15 different sizes of carbon arrows are common. Typically, the shaft of a carbon arrow is cylindrical and has a relatively small outer diameter as compared to aluminum arrows. A suitable nock mounting system has not yet been developed for the carbon shaft arrow. On prior art carbon arrows, a plastic nock with an inner bore larger in diameter than the outer diameter of the carbon arrow is fitted over the carbon arrow shaft. Alternately, a metal nock adapter cap with an adhesively attached nock is fitted over the carbon arrow shaft. However, the larger nock creates turbulence because of its expanded outer diameter. Turbulence is undesired because it interferes with the accuracy and speed of the arrow's flight.
About 9 or 10 different sizes of aluminum-carbon arrows are common. Typically, the shaft of an aluminum-carbon arrow includes an inner cylindrical aluminum portion with a carbon wrap on the outside thereof. Aluminum carbon arrows typically have an outer diameter between the sizes of aluminum and carbon arrows. The aluminum-carbon arrow has the advantages of the light weight of carbon and the structural rigidity of aluminum. However, mounting a standard nock on the end of an aluminum-carbon arrow involves the same problems as with the above identified other types of prior art arrows. An A.C.E. nock which fits within the inner diameter of the shaft is available for one size of aluminum-carbon arrow, however the A.C.E. nock is only adapted for fitting within one specific shaft size.
A problem associated with all three types of arrows involves situations when an arrow strikes the back end of another arrow, which is sometimes referred to as a robin hood shot. A robin hood shot often damages or destroys the nock and splits the arrow shaft. With a plastic nock, a robin hood shot usually destroys the nock and damages the arrow. With a plastic nock and metal adapter, a robin hood shot usually destroys the nock with the adapter and shaft absorbing the force of the oncoming arrow, which may still damage the arrow depending on the force of the blow and the strength of the adapter. Any damage to the arrow shaft should be avoided because of their relatively high cost in comparison with the nock.
Another problem in the archery art is that all of the above mentioned arrow types needs a particular size of nock. This requires that numerous types of nocks be provided which may not be optimal or even compatible to more than one size arrow. Nocks are broken more frequently than nock adapters, so large volumes of inventory are required to adequately stock nocks for the various arrow sizes.
What is needed is a nock adapter which is smaller in size to reduce the drag on the arrow. Also what is needed is a low weight nock adapter capable of providing a nock mount for all the various available arrow sizes which is adapted to mount at least one of the standard or A.C.E. nock. A further need exists for a nock adapter which allows for easier attaching and detaching of the nock. Yet another need exists for a nock adapter which minimizes damage from robin hood shots.